1. Field of the Invention
The present invention relates to a method of using a reversible thermosensitive recording medium capable of forming an image therein and erasing the image therefrom by controlling thermal energy applied to the recording medium, and also relates to the above-mentioned reversible thermosensitive recording medium.
2. Discussion of Background
One of the representative examples of the reversible thermosensitive recording media which have been put to practical use is a reversible thermosensitive recording medium as disclosed in Japanese Laid-Open Utility Model Application 1-165286. Basically, the above-mentioned reversible thermosensitive recording medium comprises a reversible thermosensitive recording layer where an organic low-molecular material is dispersed in a matrix resin. A white opaque image is formed in this recording layer by imagewise heating the recording layer. The white opaque image can be erased when the recording layer is again heated at a temperature that is different from the temperature for image formation so as to return the recording layer to the initial transparent state.
The other example is a reversible thermosensitive recording medium provided with a reversible thermosensitive recording layer comprising an electron-donating coloring compound and an electron-accepting compound as the main components, as disclosed in Japanese Laid-Open Patent Applications 5-124360, 6-210954, 5-92661, and 4-303680. In this kind of reversible thermosensitive recording medium, a color-developed state and a decolorized state are relatively formed by controlling the temperature of the recording medium in the heating operation and/or the cooling rate after the heating operation, thereby achieving image recording and erasure. As the electron-donating coloring compound, a leuco dye is usually employed, so that a variety of colors such as black and blue can be selectively produced.
Such reversible thermosensitive recording media are widely used, in particular, in the form of a card. In the conventional card-shaped reversible thermosensitive recording medium, for instance, a reversible thermosensitive recording portion is disposed in the center of the card, and a printed image portion is provided along the edge of the card, as proposed in Japanese Laid-Open Patent Application 8-15079. In the above-mentioned configuration, the reversible thermosensitive recording portion and the printed image portion are separately arranged, and an image formed in the former portion is not associated with an image formed in the latter portion. Namely, the reversibility of the reversible thermosensitive recording medium is not fully used in the conventional recording method.
Accordingly, a first object of the present invention is to provide a method of using a reversible thermosensitive recording medium, capable of fully exhibiting the function of reversibility of the reversible thermosensitive recording medium.
Further, a second object of the present invention is to provide a reversible thermosensitive recording medium for use with the above-mentioned method.
The above-mentioned first object of the present invention can be achieved by a method of using a reversible thermosensitive recording medium comprising a support, a reversible thermosensitive recording layer of which color tone is reversibly changeable with the application of heat thereto to change the temperature thereof, and a printing layer which bears a printed image A on the support, the above-mentioned method comprising the step of forming an image B in the reversible thermosensitive recording layer by heating the recording layer to an image formation temperature to complete a single composite image in combination with the printed image A.
The second object of the present invention can be achieved by a reversible thermosensitive recording medium comprising a support, a reversible thermosensitive recording layer of which color tone is reversibly changeable with the application of heat thereto to change the temperature thereof, and a printing layer which bears a printed image A on the support, wherein when an image B is reversibly formed in the reversible thermosensitive recording layer by heating the recording layer, the image B completes a single Composite image in combination with the printed image A.
Alternatively, the second object of the present invention can also be achieved by a reversible thermosensitive recording medium comprising a support, a reversible thermosensitive recording layer of which color tone is reversibly changeable with the application of heat thereto to change the temperature thereof, the reversible thermosensitive recording layer bearing an image B therein, and a printing layer which bears a printed image A, wherein the image B and the printed image A in combination constitute a composite image.